Cabo Pulmo was designated a United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage site in 2005 and was added to the Ramsar List of Wetlands of International Importance in 2008.

Photo: Christine Delsol, Special To SFGate

Cabo Pulmo was designated a United Nations Educational, Scientific...

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Cabo Pulmo is a remote knob of classic Baja landscape and adjacent to one of the oldest coral reefs on North America's Pacific coast.

Photo: Christine Delsol, Special To SFGate

Cabo Pulmo is a remote knob of classic Baja landscape and adjacent...

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A glimpse at the town of Cabo Pulmo.

Photo: Christine Delsol, Special To SFGate

A glimpse at the town of Cabo Pulmo.

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Cabo Pulmo is a blip on the tourism radar, a blessing for the wildlife and untouched landscape, but all that could change if a massive development planned for the area plants 30,000 hotel rooms there.

Photo: Christine Delsol, Special To SFGate

Cabo Pulmo is a blip on the tourism radar, a blessing for the...

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A local travels along the road through Cabo Pulmo's frontier-like landscape.

Photo: Christine Delsol, Special To SFGate

A local travels along the road through Cabo Pulmo's frontier-like...

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A planned development could bring masses of tourist to Cabo Pulmo's pristine waters and wild surroundings.

Photo: Christine Delsol, Special To SFGate

A planned development could bring masses of tourist to Cabo Pulmo's...

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Despite the speed of large-scale tourism development in Mexico, remote Cabo Pulmo is not lost yet. The approval for development of the area will have to be reviewed again.

Photo: Christine Delsol, Special To SFGate

Despite the speed of large-scale tourism development in Mexico,...

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The degradation of the reef in Cabo Pulmo's waters led to the campaign that turned the area into a 17,560-acre marine reserve. Once depleted wildlife is making a recovery.

Cabo Pulmo, a remote knob of classic Baja landscape with an underwater world singularly blessed by nature, slumbered for decades on the peninsula's East Cape. It rarely made a blip on the tourism radar except for avid fishermen, divers, and in more recent years, windsurfers and adventurous tourists from Los Cabos, about an hour's drive away. Despite a valiant, and successful, effort by Cabo Pulmo's residents and fans to get the federal government to protect its uniquely rich waters as a marine national park in 1995, today it is the target of massive development that would plant 30,000 hotel rooms — equivalent to another Cancun — on the sand dunes, along with a marina for 490 boats, shopping centers and two golf courses.

You don't have to be a math savant to figure out that the area, which now has only about 80 scattered residents, will be irrevocably changed. Not only will the wild, frontier-like atmosphere be replaced with the crowds and bustle of another mega-resort, by most scientific assessments a unique ocean ecosystem will be destroyed.

The only coral reef in the Gulf of California, at an estimated 20,000 years one of the oldest on North America's Pacific coast, lies off of Cabo Pulmo's shore. Parts of the shallow coral mountain lie just 10 miles offshore, sheltering 226 fish species. In addition to sea turtles, dolphins, tiger and bull sharks, and migrating humpback and blue whales, Cabo Pulmo is one of the few spots in the Americas where rare whale sharks — the largest fish alive — congregate near land.

Despite Cabo Pulmo's remoteness and relative obscurity, locals began seeing fewer fish in the 1990s, while those there were had retreated farther out into the ocean. Primarily because of commercial fishing boats' practice of dragging their anchors through the coral to snag the valuable fish species, what had once been dubbed "the world's aquarium" by pioneering diver Jacques Cousteau was increasingly barren of life.

The efforts have paid off: A study released by the Scripps Institution of Oceanography in August 2011 found Cabo Pulmo's "biomass" — total weight of living species — increased by 463 percent from 1999 to 2009. The report credited the park’s success largely to enforcement of protective regulations by local boat captains, dive masters and other locals.

Octavio Aburto-Oropeza, one of the report's authors, wrote in a Scripps article about the study, "No other marine reserve in the world has shown such a fish recovery." Residents have noticed an increase in the number of fish, including a monumental spike in the number of sharks. Some species are migrating from other areas to the now-healthy reef.

Federal environmental officials did impose stricter environmental conditions while green-lighting the project a second time March 1, 2011, after a resident filed for a review. Those conditions would not stop the pollution from vacation activities and sediment from construction and dredging, or the addition of thousands of homes for resort employees in a region where fresh water is scarce.

Environmentalists, backed by scientists from Mexico and around the world, brought Cabo Pulmo’s plight to UNESCO’s attention last May. The alerts brought representatives of UNESCO, the Ramsar Convention and the International Union for the Conservation of Nature to Cabo Pulmo in November to evaluate the potential impact of Cabo Cortes and to hear from both the affected communities and the developer. The organizations called for Cabo Pulmo to be added to UNESCO's "World Heritage in Danger" list and the Montreux Register under the Ramsar Convention as a wetland in danger.

The 2009 abandonment of the once-ballyhooed "Escalera Nautica" project, which aimed to create a route of marinas and tourist sites up and down the Baja peninsula, and the sputtering, three-decade history of the still-unrealized Loreto Bay project, would seem to argue against the Cabo Pulmo development on financial as well as environmental grounds.

Despite the runaway-train speed of large-scale tourism development in Mexico, Cabo Pulmo is not lost yet. SEMARNAT ruled last August that the 2008 environmental permit it granted for Cabo Cortes no longer is valid, and that it would review that decision.

To learn more about the effort to stop development at Cabo Pulmo, go to the Wildcoast website. The international conservation organization, which works in the Californias and Latin America, offers volunteer opportunities and is collecting petition signatures.

This article has been updated since it first appeared online.

Former Chronicle travel editor Christine Delsol is the author of "Pauline Frommer's Cancún & the Yucatán" and a regular contributor to "Frommer's Mexico" and "Frommer's Cancún & the Yucatán."